This invention relates generally to endoscopic surgery and more particularly concerns instruments used in carpal tunnel endoscopic surgery.
Surgery to decompress the carpal tunnel and therefore the pressure on the median nerve has been known for many decades. The longest known procedure typically involves an incision ranging from two to five inches in length and requiring as much as six weeks to heal. Since the introduction of endoscopic surgery, the procedure involves only one or two relatively small incisions, resulting in significantly faster recovery. However, existing endoscopic instruments produce new and unanticipated problems. Such instruments, when forced into the carpal tunnel as a step in the surgical procedure before decompression, result in new postoperative complaints of pain or numbness, especially in the middle and ring fingers, in a high percentage of existing endoscopic carpal tunnel surgery patients. It is estimated that fifteen to twenty percent of carpal tunnel surgery patients proffer such complaints after use of these known instruments.
It is, therefore, an object of this invention to provide instruments specifically suited to carpal tunnel endoscopic surgery. It is also an object of this invention to provide a carpal tunnel cannula of diameter suited for insertion into the carpal tunnel. Another object of this invention is to provide a cannula having a diametrically narrowing tip to facilitate its passage into the carpal tunnel. A further object of this invention is to provide a cannula having a matted interior surface to enhance visual display of the surgical area. Another object of this invention is to provide an obturator having a plow shaped tip facilitating passage of the obturator tip in the carpal tunnel. In another object of this invention is to provide a rasp specifically suited for manipulation in a carpal tunnel cannula. It is also an object of this invention to provide a rasp configured to guide its roughened surface through the cannula slot to the ligament to be treated. Another object of this invention is to provide a rasp configured so as to limit the distance to which the roughened surface may be radially extended through the cannula slot. And it is an object of this invention to provide a rasp configured to permit longitudinal alignment of the roughened surface with the ligament to be treated.